"By the end of the 21st century," writes Reason magazine science editor Ronald Bailey in his book "Liberation Biology," "the typical American may attend a family reunion in which five generations are playing together. And great-great-great grandma, at 150 years old, will be as vital ... as her 30-year-old great-great grandson with whom she's playing touch football."

UCLA futurist Gregory Stock predicts in "Redesigning Humans" that the genetic engineering of progeny for health, intelligence, physical beauty, even sociability, will be so successful that procreation through intercourse will be deemed "too unpredictable," making "laboratory conception ... obligatory rather than optional."

Princeton biologist Lee Silver believes fervently, as described in "Remaking Eden," that the wonders of human redesign will eventually lead to a "special point" where our posterity will create themselves into a "special group of mental beings who "are as different from humans as humans are from primitive worms. ...'Intelligence' will "not do justice to their cognitive abilities. 'Knowledge' does not explain the depth of their understanding. ...'Power' is not strong enough to describe the control they have over technologies that can be used to shape the universe in which they live."

The prospect of a 150-year-old living human being sounds fantastical. So does pre-designing children or future generations with godlike powers. But many futurists and scientists say we humans are about to seize control of our own evolution.

If the impeders of scientific progress can just be pushed out of the way, they predict, the wonders of science and biotechnology will re-create us into superior beings who will live longer, look better, play harder and think smarter than any of us can even dream of doing today.

Others (including this writer) see such scenarios as more hype than hope.

Some of us also worry that advocates of unfettered research are changing science from a means into an end, a belief system rather than a method.

Indeed, "bioskeptics," as they are sometimes called, see a utopian ideology of "scientism" forming that threatens to upend society's belief in human equality and unleash a "new eugenics," in which Aldous Huxley's dystopian vision of mind control from "Brave New World" could become a reality.

Look out America: The trajectory of science is coming into conflict with venerable human values. Which side prevails will depend less on what scientists can do than upon the ethical principles that govern society in an era of biological control.

In the United States today, every human being who is born possesses full moral and legal rights. But this is under pronounced assault. Influential philosophers, such as Princeton University's Peter Singer, assert that basing an individual's moral value on humanhood is irrational and grounded in outdated religion.

In place of humanness as the criterion for ultimate value, these advocates offer "personhood theory," in which rights belong to "persons," a status earned by any organism or machine possessing minimal cognitive capacities.

If personhood theory ever governs society, the impact would be incalculable, for as futurist James Hughes writes in "Citizen Cyborg," "Persons don't have to be human, and not all humans are persons."

Opponents of personhood theory warn that it would lead to the most vulnerable humans being exploited as mere objects.

They note that some supporters of personhood theory already advocate infanticide for profoundly disabled babies and organ harvesting from people diagnosed to be in a persistent vegetative state.

The already simmering humanhood versus personhood controversy is going to boil over as our scientific and biotechnological capacities advance.

For example, what if it becomes technologically feasible to create cloned human embryos and gestate them in real or artificial wombs to fetal stage for use in drug testing or for organ procurement? (Such experiments have already been conducted successfully in cows.)

Those who believe that humanhood provides intrinsic value argue that such "fetal farming" should be prohibited because it reduces nascent human life to the status of a mere harvestable commodity.

Personhood theorists, on the other hand, would tend to support using cloned fetal nonpersons to save the lives of persons and to reduce the suffering of animals currently used in medical research, which are seen as having greater moral value because they possess higher cognitive capacities.

New Jersey has already legalized the creation of cloned embryos and their gestation through the ninth month.

Another issue touching on the meaning and importance of human life is the creation of animals called chimeras that have been genetically engineered to contain some human DNA.

Promoters of this research point out that great good could result, for example, from obtaining human proteins from the milk of these altered animals for use in pharmaceuticals, a process known as "pharming." Other than a scattering of environmentalists and animal rights activists, few object to creation of these "transgenic" animals.

But important questions remain: How much human DNA in an animal is too much? (James Hughes believes that chimps should be "uplifted," that is, enhanced genetically to "have human intellectual capacities." That's a way, he says, of proving that "personhood not humanness" should "be the ticket to citizenship.")

Should any animal DNA ever be permitted to re-engineer human embryos?

Such experiments are far from unthinkable. A new social movement called "transhumanism" advocates the creation of a "post-human species," which would include using animal genes in progeny to increase strength or make senses more acute.

Once having children was generally conducted in a simple way: Men and women got married, made love, and had babies -- although not always in that order.

To the delight of some and the dismay of others, human reproduction has become a far more complicated matter.

Infertile couples now conceive through in vitro fertilization. Women who can't carry a child can arrange to have their baby gestated by a surrogate birth mother. Gay and lesbian partners are demanding the right to marry and have families. Sex selection has already begun.

The social controversies raised by these behavioral changes, already white-hot, are going to grow even more intense as cutting-edge procreative advances offer ever-greater latitude to those wanting children and more-precise control over the kind of children they have.

But critics worry that our growing mastery over reproduction could slide from liberty into license and even into reproductive anarchy. Look for these issues to cut through the body politic like a laser in the coming decades:

-- Is there a right to reproduce?

This issue strikes at core beliefs about the importance of natural limits, age, gender, sexual orientation, feminism, traditionalism, normality and the purposes of becoming a parent.

-- Should a 65 year-old woman be allowed to receive technological assistance giving birth? How about an 80-year-old?

-- Should a man be allowed a uterus transplant so he can become a mother, as bioethicist Joseph Fletcher suggested?

-- Will it be acceptable for a woman to use animal or artificial wombs to gestate her baby so as not to have her professional life inconvenienced by a wanted pregnancy?

-- Is there a right to have genetically related offspring? Reproductive cloning is off the table for now because cloning isn't safe. But what if it were? Some bioethicists are already suggesting that outlawing reproductive cloning, at least for gay or infertile couples, would be unconstitutional because "procreative liberty" includes the right to have biologically related offspring.

-- Is there a right to genetically engineer offspring? Eradicating genetic disease is one thing. But there is a chorus of advocates who want to harness our growing knowledge of the human genome to "improve" our children through germ line genetic manipulations.

James Watson, co-discoverer of the DNA double helix, argued that prospective parents should use biotechnology to eradicate undesirable traits -- or fabricate wanted enhancements -- in their children.

More bluntly, bioethicist Gregory Pence suggested in "Who's Afraid of Human Cloning?" that parents should be allowed to use biotechnology to "aim for a certain type" of child "in the same way that great breeders ... try to match a breed of dog to the needs of a family."

-- Will the artificial womb affect the right to abortion?

Within 20 years, it is expected that artificial wombs will be available to save troubled pregnancies. If so, it is foreseeable that some anti-abortion states would pass laws requiring women wanting mid- or late-term abortions to instead have their unwanted fetuses saved through transfer into artificial wombs.

Science is opening the door to procreative "quality control." Whether society will permit made-to-order children will be the subject of debate for years to come.

All this begs the question: Who decides?

Some believe scientists should have the exclusive say because of their unique expertise. Thus, bioethicist Rahul Dhanda, wrote in "Guiding Icarus," that science "knows what is good for society, like a parent knows what is good for the child."

Professor Francis Fukuyama, a noted public intellectual, took a different view in "Our Posthuman Future." "True freedom means the freedom of political communities to protect the values they hold most dear," he wrote, "and it is that freedom that we need to exercise with regard to the biotechnology revolution today."

The intellectual foundation is being laid for lawsuits that will seek a constitutional right to conduct scientific research -- perhaps in response to passage of a new federal law outlawing all human cloning.

Some scholars believe such a right is contained in the First Amendment. In this view, scientific experimentation is analogous to a reporter's right to research a story.

If there is a right to conduct experiments implicit in the First Amendment, only a compelling state interest -- such as preventing a plague -- would justify the government infringing a scientist's fundamental freedom of inquiry.

Opponents of unfettered research say the scientist-equals-a-reporter analogy fails because granting a right to research would actually be akin to allowing a reporter to set fire to a building so he could write a story about the arson.

How all of this will turn out, nobody knows. But as Leon Kass, former chairman of the President's Council on Bioethics, has said: "All of the natural boundaries are up for grabs. All of the boundaries that have defined us as human beings, boundaries between a human being and an animal on one side and between a human being and a super human being or a god on the other. The boundaries of life, the boundaries of death. These are the questions of the 21st century, and nothing could be more important."

Wesley J. Smith is a senior fellow at the Discovery Institute and a special consultant to the Center for Bioethics and Culture. His current book is "Consumer's Guide to a Brave New World." www.wesleyjsmith.com